I. Field of the Invention
The present invention relates generally to wireless communications. More particularly, the present invention is directed to a novel and improved method and apparatus for the wireless metering of remote measurement devices which are concentrated in a single geographic area.
II. Description of the Related Art
Many industries utilize remote metering devices to monitor, measure, or record critical data. For example, utility companies use utility meters located at the customer site to measure utility consumption. The de-regulation of utility companies, such as electric power, water, and natural gas companies, has prompted these utility companies to seek technological modernization of equipment and services as a means of reducing costs in order to compete with other potential utility service providers.
In a conventional utility metering system, each utility customer is billed according to utility usage over a predetermined period of time, such as one or two months. The utility usage is measured by an electromechanical meter having a visual display such as a set of dials, or an "odometer" type display. A person, typically an employee of the utility company, periodically visits each utility meter in a service area to visually read the utility consumption as reported by the meter.
Several inefficiencies exist in the conventional utility metering system. For example, the utility company must pay a person to travel to each meter to visually read it. This may require sending the meter reader into a dangerous area. It also takes a long time for a person to physically visit each meter. Additionally, most electromechanical meters may be opened and tampered with by a person wishing to reduce his utility bill. Since the meter is typically read only about once a month, the tampering may not be evident to the utility company. Another drawback to the conventional utility metering system is that local fault detection, such as the detection of a localized blackout or brown-out condition, is not possible in real-time because the utility consumption is not measured in real time on a local scale.
Furthermore, a typical utility company is forced to maintain a very high peak-to-average usage ratio. For electrical power companies, this peak-to-average usage ratio may be on the order of 12:1, requiring the power company to maintain about twelve times as much equipment as would be required for a constant, average load. The conventional metering system does not provide any real-time way to minimize peak loading conditions. Clearly this is a very significant cost in providing utility services. Conventional attempts to control peak-to-average usage ratio include billing at a higher rate for all usage above a predetermined quantity. However, it is not currently possible in the conventional system to perform this billing increase in real time because it is not until the meter is read that the utility company can determine the amount of usage. Likewise, the prior art metering system does not monitor real-time loading conditions on a local scale in order to provide for more accurate usage forecasting and equipment installation planning.
In a competitive market, the utility company could also greatly benefit from the integration of other services with utility services. In a related area, "smart" homes are being designed which provide a high level of integration of consumer services such as telephone, cable television, computer network services, home shopping, paging, and the like. Additionally, these "smart" homes may utilize Consumer Electronic Bus (CEBus EIA/ANSI-600) technology to enable the owner to remotely control various household appliances and devices using power-line carriers over the existing power lines in the home. The purpose of CEBus technology is to allow consumer appliances and devices to work together as an integrated home or industry system. CEBus-compliant devices can share information with other CEBus-compliant devices. Among other communication media, the CEBus standard supports communication over pre-existing power line and twisted pair cabling. Power line transceivers typically use a 100 to 400 KHz spread-spectrum carrier technology, while twisted pair transceivers use a simple 10 KHz, 250 mV carrier. However, with the traditional metering system, the utility company does not have the infrastructure to take advantage of this integration.
The problems facing the utility companies in this area are similar to problems facing companies in other industries that have a need to remotely monitor, measure or control a metering device or point-of-sale. For example, mail delivery companies, such as the U.S. Postal Service or the like, generally maintain a large number of mail drop-off points. Each day, these drop off points must be checked to see if any mail has been deposited for delivery. Often times, especially in rural areas, there is no mail at the remote mailbox when the postal employee arrives to check it. The result is inefficient deployment of resources. Likewise, vending machine companies must send employees out to service remote vending machines according to a predetermined schedule, without knowing what the actual demand has been at the machine until the employee arrives. Clearly, there are many industries that face similar inefficiencies that arise from scheduled servicing of remote stations rather than event-driven demand-side management of these remote stations.
Several prior art solutions have been proposed for overcoming these efficiencies. Many of these prior art solutions involve the design and installation of new, dedicated communication systems to service the remote telemetry devices. Such prior art solutions make initial deployment of the system cost prohibitive. Other prior art solutions avoid high initial costs by using existing cellular radiotelephone systems to provide the communication link with the remote telemetry device. However, a significant drawback to these systems is their lack of capacity, preventing them from servicing large urban areas due to a potential overload of the cellular system overhead channels which would prevent normal cellular phone customers from receiving reliable service. Still other prior art solutions use unlicensed radio frequency (RF) bands to transmit their remote telemetry data, resulting in a significant loss of reliability due to interference from other unlicensed users in the same RF band.
In addition, many of these prior art solutions use one wireless transmitter for each telemetry station, even when many of these telemetry stations may be co-located. For example, a typical prior art solution may have one transmitter for each utility meter of each residential home in a neighborhood. This approach adds significantly to the initial cost of deploying a wireless telemetry system.
What is needed is a remote telemetry system which avoids the disadvantages of the prior art telemetry systems by providing real-time telemetry data information in a low-cost and efficient manner, while further providing a "gateway" for providing advanced consumer services at the remote location.